Provide the proper QSysInfo::productType on WASM

Task-number: QTBUG-110057
Change-Id: I73b78e56faa3af858f60b884d0ea36acbd7f78cf
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/global/qsysinfo.cpp

@@ -788,6 +788,8 @@ QString QSysInfo::productType()
     return QStringLiteral("macos");
 #elif defined(Q_OS_DARWIN)
     return QStringLiteral("darwin");
+#elif defined(Q_OS_WASM)
+    return QStringLiteral("wasm");
 
 #elif defined(USE_ETC_OS_RELEASE) // Q_OS_UNIX
     QUnixOSVersion unixOsVersion;